When that prophecy in one of the last episodes said something along the lines of "3 days to the end of the world", was it talking in valve time?
I'm waiting for them to do another playthrough of some mod pack. MoonQuest and the subsequent Hole Diggers were very fun to watch, and I like the team dynamic between Lewis, Simon, and Duncan.
The last thing I remember them doing as a modded playthrough was Yoglabs Hypercubed. I don't count that because it's an adventure map, and it's still only on episode three.